Journalist and best-selling author Malcolm Gladwell is an outspoken advocate of banning college football on health grounds, and his appearance on CNN’s ‘GPS with Fareed Zakaria‘ has turned up the volume another notch. Zakaria asked Gladwell to defend hiscontroversial position, and nary a punch was pulled.

Gladwell, author of The Tipping Point, Blink and Outliers, references a growing list of research studies suggesting a link between the head-impact injuries football players routinely endure during practice and games, and debilitating neurological disorders. The most troubling of these studies show evidence of chronic traumatic encephalopathy (CTE) in the brains of former college and professional football players, a disease with similarities to Alzheimer’s. CTE is only diagnosable post-brain death during an autopsy and has also been found in the brains of boxers and hockey players (although medical researchers are getting closer to diagnosing the disease in living adults).

Before the last few years of research, it was commonly thought that only head injuries resulting in a concussion or worse were serious enough to trigger long-term problems. The latest studies are showing that’s not the case—it’s not only the concussive hits that take a toll, but the ongoing subconcussive hits that many players endure multiple times during the course of a game.

A recent study of college football players who had experienced subconcussive hits showed evidence of traumatic brain injury hours after a game and, in some cases, six months later. Researchers administered a blood test to players to track a protein called S100B that indicates damage to the blood-brain barrier. When enough of the protein enters the blood stream, the body attacks it as a foreign invader, producing antibodies that can later re-enter the brain and cause long-term damage like epilepsy and dementia.